Fluid-pressure-operated valve



April 23, 1929. P. M. G RANT FLUID PRESSURE (SPERATED VALVE Filed Feb. 13, 1928 2 Sheets-Sheet l April 23, 1929. P. M. GRANT 1,710,055

' FLUID PRESSURE OPERATED VALVE Fi1ed.Feb. 13, 1928 '2 Sheets-Sheet 2 Patented Apr. 23, 1929.

- oniri o s'rn'res minis PATENroFFiee,

PATREGK 1Y1. (El-RANT, OF CHICAGO, ILLINOIS.

Application filed February llhis invention relates to fluid pressure operated. valves zind is particularly adaptable for use in connection with signalling devices, as, for cxiunple, in connection with air h eke systems used on railroads, and will be described as employed in that connection.

One of theolojeets oi the present invention is to provide a construction,whereby an nudible signal such use whistle, or the like, will he uutoniuticollv controlled, as in the. present instance, by the 'l'iuid pressure maintained :in the air b nice system.

Another object 01 the ii'ivention is to pro vide means to adjusting the valve control elements to enable the proper posntioning of unions parts in a manner to facilitate the assembling of the device, and to obtain the inuxiinun'i etliciency.

Another object of the invention is to provide, in conibiinttion with other tortures, an ndiustul'ile stop for limiting the movement of the valve controlling eleinents in order to nmintuin the proper relation of ports and in sure the elij'ectuo-l operation of the device.

Another object of the invention is to provide hnovcl means whereby, he whistle or other sigiuillingg device may be iictuuted by pressure received directly from the source of fluid supply. 1

iinother object of the invention is to pro vide a novel ii struction and arrangement wherein fluid under pressure isndn'iitted to the whistle or other signalling device when the train line is hind, and wherein, the supply of liuid to the whistle is shut olii' untoinuticzilly. bv the pressure itself when the Another ob'icct'o'i the invention is to provide :1 device wherein dir .et coinnuinicntion,

is estublished betwi the whistle and the source of fluid pressure supply when the train line is bled, :ind wherein, the fluid troni J break the coniniunicution to shut oil the supl l}; oi lluid to the whistle when. the vent in the train line is closed.

Another object oi? the invention is to provide men n: whereby the duration of time between the closing); oi the vent in the train lin: and the closing oi the whistle valve unify be varied as desired.

A further ohject oi? the invention is to provide n'iezmsitor assisting the linti d pressure in positively senting the whistle valve.

A still further object of the invention is to improve devices of this chnrncter in sundry said source oi suppl is utilized to 3, 1928. Serial No. 253,844.

details hereinafter described and particularly pointed. out in the appended chiiins.

One embodiment oi. the invention is shown,

tor ilhiistrative pi'irposes, in the accompany in dru' vin z', in which Fig. 1 is a central longitudinal sectioiul ele ntion through the device, taken substantially as inilicoted by the line 11 oil? Fig. K

2 is it transverse sectional elevation taken on the line 2-2 of Fig. 1.

Fri 3 is it sectional cle ntion through the iluid strainer, token on the line of Fig. 1. i i I Figvkt is it transverse sectional elevation taken on the line 4- 1: 01 Fig. 1.

Fig. 5 is u 'ii'rag'inentnry sectional plan view taken on tho'line 5 5 of Fig.

Fig. (i is it fragmentary sectional plan view similar to 5, showingthe piston or inevuhle abutment in a changed. position for opening: the inlet valve, and i Figs. 7 and 8 are views of the 'nterchungeubletuhes having; openings oi dii'ierent sizes, adopted for use in varying the period, of time between the closing of the train line vent on d the closing of the Whistle or outlet valve.

Referring to the drawing, the illustrative embodiment of the invention shown, coiupris k a hot sing or 2 :using 10 adopted to be positioned in the cziboi 2i locomotive or the like, the sui d housing being provided with an ei i'ged rear end portion 11 and a. reduced torwin'deiul portion 12, the portion 11. having u cent 'ally disposed longitudinal bore 1?) formed therein, and provided with screw threads nduptedto receive a cap it, while the reifluced end portion 12-is provided with screw threads for receiving thereon an outlet vnlve .titting having it centrally disposed longitudinal bore mztending therethrough.

Mounted to slide longitudinally in the bore 13 :1 piston or abutment 16 adapted to receive at rod 17 having one of its ends screw thrci ded to engage threiuled openings in, the plates 18 and 18 ot the piston, and jtlll] nut 19 for holding the said plates together and ill) chamber 21 and a valve opening provides or forms a valve closing pressure pressure chamber 22 within the housing or casing 10. The casing 10 is also provided with a port 23 communicating with the chamber 21 and with a pipe 2st tylfiiiying, in the present instance, an air brake system or the train line of an air brake system. in which a supply of fluid pres sure is maintained for operating the brake mechanisms; i

To the outer or forward end of the valve fitting is connected, by neans of a pipe 25, an audible signal deviceQtS shown in the pres ent instance as an air whistle adapted to be operated by the bleeding or venting of the train line, as may be done by a member or the train crew or by the parting of the train, and I in either case the engineer or other person in the engine cab receives the signal caused by the venting 0t thetrain line, or is notified oi any abnormal condition in the air brake system.

For operating thewhistle the fittinglb is pr vided with a valve seat 27, and slidably mounted in the bore of the fitting 15 is a valve member 28 provided with aplurality of annularly spaced longitudinally oisposed grooves or channels .29 on the periphery thereof for admit-ting fluid under pressure to the whistle when the valve member 28 is removed from its seat 27 by reason of a vent in the train line.

For actuating the whistle valve. the valve member 28 is connected to the rod 17 in a manner to be moved into and out of engagement with the valve seat 27 when the piston 16 is moved longitudinally of the bor 13 formed in the enlarged portion 11 of the casing 10, the connection being accomplished by means of a head portion 3t) formed on the end of the rod 17 and iositioned within an enlarged central chamber 31 termed in the valve member 28, the rear or open end of the chamber 31 being partially closed by a wall portion 32 through which extends a neck portion 83 formed centr: lly ot the rod l7 and serving to connect the head 30 to the end of the rod.

The method otassemblingthe valve mem ber 28 with the end ot the rod 17 is clearly illustrated in Fig. a. wherein the chamber 31 shown. as extending outv dly to the face of the valve member as indicated at El and the opening n the wall portion 32., in which the necli portion 33 is positioned. is shown as extending outwardly to the surface of the valve member asindicated at 35.

The valve member 28 is provided with a centrally disposed longitudinal chamber 36 communicating' with the chamber 31 and in the chamber 36 is mounted a compression spring 3'? adapted to bear against the head portion 30 of the rod 17 and the interior or bottom portion of the chamber 36. It will be observed from the foregoing description that when the piston 16 is moved to the left. as viewed in Fig. 1 the'head portion 30 will move a substantial distance within the chamber 31 before engaging the wall portion 320i the valve member 28 and before withdrawing the varve from its seat 27, thus providing a degree of lost motion in the connection between the rod 17 and valve member 28, and that. the head after engaging the wall portion 32,,w1ll, by reason of any continued n; vement of the piston 16, open the whistle head 30 to'compress the spring in the chamber 36, thereby securely seating and holding the valve member 28 upon the seat 27.

The reduced end portion 12 of the casing '10 is provided on its interior with a central T ng 3S. and formed integrally with the g" between the said opening 38 and chamber 2L a wall portion 39 serving as a guide and support the for vard or outer end of the rod 1?, and in which are formed a plurality 0t annulariy spaced ports or openings L IO through which fluid under pressure from the chamber is admitted to the whistle valve.

For supplying fluid to the whistle and whistle valve actuating means, as well as to the [1'90 10 may be. provided with suitable ports, chambers, controlling means and a supply piae d adapted to communicate ,with a air comressor or other suitable source of fluid supply.

By reference to Fig. 1 of the drawing. it will be noted that the su ply pipe i1 is screw threaded or otherwise suitably connected to a portion of the casing 10 and is adapted. to communicate by means of a port 1-2 with a fluid cleaning chamber it) formed in the lower portion of the casing and having its outer open end portion closed by means of a screw threadedplug M. lhe plug -l-l provided within the chamber l3. with a centrally disposed longitudinally extending reduced annular wall portion having a plurality of longitudinally extending annuh rly spaced openin or slots 5 b formed therein. and provided on its periphery with a fabric covering all, such as a line screen or the like, adapted to cover said openings in a manner to strain or clean the fluid admitted to the clcal'iing chamber 43 ot any dust, cinders or other toreign matter before it passes to the whistle valve and valve actuating mechanism.

Formed in the lower portion of the casing 10 adjacent the chamber 43 and separated ther from by a wall 48 is a. distributor chamber l9 adapted to communicate with the interior of the screened wall portion d5 oi the plug 44;, the inner end of which is termed to in line of t ie air brake system, the casing llO LII

iii)

fit snugly in an opening 50 formed in the wallv 4:8.

Communicating with the distributor chainher 419 is a port 51 in which is mounted a hollow tube 52 through which the fluid. may pass trom the chamber 4:9 into the port- 23 and thence to the mambo 21 and throu 'h the pipe 24.- to the train line of the air brake its end port ions with the chamber 49 and with its opposite end portion with an inlt valve chamber 54: formed in the casing 10, the said chamber having its outer or open end portion closed by means of av screw threaded plug 55. Adjacent and communicating with the chamber 54 is a passa 56 formed in the side wall of thecasing 10 in an'ianner to provide communication between the said chamber 5 1 and the chamber 22, for supplyingfluid to the chamber 22 for actuating the outlet or whistle valve and whistle.

Mountedin the passage 56 is an inlet valve 57 having; a stem 58 provided with grooves .59 termed therein tor permitting the passage ot fluid "from the chamber 54 to the chamber 22, the said valve 57 being adapted to engage a. valve seat 60 formed in the casing 10 adjacent and sun'oimdin the passage to. The valve stem 58 is extended outwardly beyond the valve 57 in a. manner to enter a centrally disposed longitudinal bore 61 formed in the plug 55 in a manner to bo nuided therel'iy, while a compression spring 62 is positioned to surround the outwardly extending portion of the valve stem between the plug: 55 and the valve 57 in a manner to resiliently hold the valve on the seat 60.

The plate '18 oi the piston 16 is DTUVllltt on its periphery adjacent the wall of the easing: 10 with an annular groove 63 positioned th reon in a. manner to receive the inner end of the valve stem 58 when the piston occupies its real-most position with'the whistle valve closed as illustrated in Fig. 1 of the drawings, the groove 63. including; aim-mining surface, as indicated by the reference character G l. to Facilitate the removal oil the valve stem out wardlv from the groove when the piston is Screw threaded into the cap 14- is a stud 66,

the exposed end portion of which may be adjustably positioned with respect to the cap and secured in such adjusted position by means of a j am nut 67 for limiting the rearward movement of the piston or abutment 16, thereby determining the movement of the valve member 28 with respect to its valve scat 27, while anannula/r rib 38 serves to limit the movement of the piston in the opposite or forward direction, and also to keep the pis ton in proper alignmentwith the bore 13. For providing further adjustmentof the whistle valve actuating means, the rod 17 my be adjusted longitiulinally with respect to the piston and secured in such adjusted position by means of the jam nut 19.

a The operation of the device is as follows Inasmuchas the iluid pressure from the air compressor orthe like, substantially constant, and so long as the degree of operating pressure maintained in the train h' e. chamber 21 and chamber 22, is substantially uniform, the piston 16 and valve elementQS will remain in the position shown in Fig. lot

the drawing, but it, for any reason, the train line is bled or the pressure therein reduced as, for example, by the giving of a rope si 'nal by a member ofthe train crew, thereby reducing the measure in the train line and chamber 21, the substantially maximum opcrating: pressure retained in the chamber by reastm of the seating ot' the valve member and valve 57011 their respective seats, will lorccthe piston 16 rezn'wardly oi the casing and longitudinally of the bore 13 in a inanner to cause the head portion 230 of the rod 1.? to engage the wall portion 32 ol" the valve member "38. and to withdraw the said member 28 -trom engagement with thevalve seat 27, thereby 3 ermitting the fluid pressure in the chamber to escape through the pipe and operate the whistle 2-". While the piston 10 is being moved rearwardly in the casing and the valve member 28 removed from seat 27, the camming surface in ct th: annular groove 63 will engage the end of the valve stem and move the valve 57 away from its sent (it) against the action of the spring (52, thereby permittinnfluid from the cmnpressor or other source of supply to enter 7 the chamber through the port 53, chan'ibcr 5-:l and passage hththus providing a lluid pressure directly from the source oil supply for continuously operating the whistle or other signalling device so long as the vent in the train line remains open. Although a portion of the fluid pressure from the source oil? s-iupply will enter the train line and escape I through the vent therein, it will be understood that inasmuch as the whistle 536 is capable of being operated by comparatively low pressure, there will be suilicient 'tluid pressure entering the chamber to continue the operation oi the whistle, notwithstanding, th

fact that a portion of the pressnre'irom th source of supply may enter the train line while it is being bled.

Upon closing the vent in the train line, a portion of the fluid from the air compressor or other source of supply will continue to,

enter the chamber 22 by way of the passage 56, and, atthe same time, a portion of the.

' formed in the casin It will be noted that the opening in the tube 52 is of greater cross sectional area than that oi theport- 53, and th by reason of this fact, a greater amount of "u will into the train line and chamber 21 in a given period of time than will pa the communicating ports and oassages into the chamber As the p essure in the train line and chamber 21 build; up, the piston 16 will be moved longitudinally and forwardly of the casing 10 to cause the valve member 28 to engage the valve seat 2?, thereby preventing further escape of tluid from the chamber but stillpermitting the fluid pressure to enter the said chamber 22 by way of he pas- 56, and as the pressure in the c-iamber ,21 continues to build up, the piston 16 will continue its forward movement lHl'li-G easing againstthe relatively low pressure in the chamber'22 and against the action of the spring 37, thereby compressing the siting 3 and securely seating the valve member 2 upon the seat 27. i As the piston continues its forward movement in the casing after closing the whistle valve, the fluid pressure entering' the chamber 22 will be built up and compressed by reason of the rela l ely greater pressure in the chamber 21; until the degree of pressure in the chamber is s1 "tantially equal to the pressure in the train line and chamber 21, and when the piston has reached the position shown, in l, the valve stem 58 will, occupy a position in the annular groove 63 of the plate 18 as shown in Fig. 5 with the valve 57 in engagement with the seat- (30, thereby preventing the escape ot pressure from the chamber 2 understood that the spring 62 p the outwardly extendirq portion of the valve stem 58 will be 'sulliciently strong to resistthe pressure in the chamber After the ventin the train line is closed and the movable parts of the dev'ce returned to the position shown in Fig. 1 the pressure in the train line and c mber 21 will retain the parts in the position shown until such time as the train line is again bled.

For va the pt l of time during which the whistle valve wi l remain open "for 01 era {the whistle alter the vent in the train hneis closed, a plurality of tubes 52 (Figs. 1, 7 and 8) maybe provided with openof time during which the whistle valve remains open after closing of the vent in the train line will be of proportionately short duration, due to the fact that a greater amount of fluid pressure is permitted to pass from the distributor chamber 1-9 into the train line and chamber 21, thereby causing the pressure to build up more rapidly in the train line and chamber 21, after the vent in the train line is closed, and it will be obvious also that if a tube having an opening of relatively smaller cross sectional area be positioned between the chamber and port 51, the peri "l of time during which the whistle valve will remain open after the train line vent is closed will be of proportionately long duration, due to the fact that a lesser amountof fluid is permitted to enter the train line and chamber 21, therel Jy requiring more time to build up the pressure in the train line and chamber 21 to a degree sufficient to move the piston longitudinally of the casing and close the whistle valve.

If desired, a compression spring 69 of suitable strength, depending upon the degree of operating pressure used, may be provided and suitably positioned between the stationary cap 14; and movab e abutment or piston 16 for i Istin the pre sure in the chamber 21 in moving the piston longitudinally of the bore 13 to seatthe valve member 28.

As an additional precaution against the entranceof dust, Cinders or other foreign matter to the valves or valve actuating parts of the device, the pipe 2% may be provided with a screen 70 adapted to be held in proper position by means oi a flange portion '71 positioned between the end of the pipe 24 and a shoulder 7 2 formed on a portion of the cas ing. v i

It will be obvious from the foregoing specification that the present invention provides, among other features, a novel construe-tic and arrangement whereby a suitable gnarling device may be operated by the fluid pressure employed to operate an air brake system when a vent in the system is opened and wherein the elements employed for controlling the operation of the signalling" device are automatically actuated by the lluid pressure from a suitable source of supply and the pressure in the air brake ystem.

It will be obvious also that the present invention provides novel means wherebythe struction and arrangement whereby the period 0t time between the closing of the vent in the train line and the closing of the signal actuatingmeans may be varied as desired.

Obviously, the present invention is not limited to the precise construction and arrangementshown and described, as the same may be variously modified without depart ng Cir from the spirit and scope of: the invention as set forth in the appended claims. Moreover, all of the'iteatures oi the inventionneed not he used conjointly, as the same may be used to advantage inwufiously di'tii'erent combinations and sub-conibinations. I

d hat I claim as my invention and desire to secure by Letters Patent is:

1. A lluid pressureoperated valvecomprising a casing having a centrally disposed longitudinal bore formed therein, a movable abutment positioned in said bore in a manner to form a plurality of chambers within said casing an outlet valve communicating with one o't said chambers, means carried by said abutment and 'co'unecteiil to said valve for opening and closing the valve when the abutment is moved longitudinally of said bore, a pipe of, an air b 'ake systemcommunicating with the other of said chambers,means for admitting fluid. under pressure to said chambers and sy ten'i, an inlet valve for controlling the passage of liuid to and from said one oi: said chambers in a manner to cause the fluid pressure in ya i last mentioned. chan'iber to open said inlet and outlet valves when a vent in said system is opened and the fluid pressiu'e in said other ou said chambers is reduced and means :tor controlling the passage of fluid to the other of said chambers and said system in a manner to cause the fluid pressure in the said other of said chambers to close said inlet and. outlet valves when the vent in the system is closed and pressure in said other of said chambers is restored.

2. A fluid pressure operated valve comn'isinp' a casing having a centrally disposed bore e, tending loi'igitudinally therethrough, a movable abutment positioned in said here in a manner to term a valve opening press are chamber and a valve closing pressure chamber within said casing, an outlet valve communicating with said valve opening pressure chant ber, means lrried by said abutment. and con uected to said valve tor opening; and closing the valve when said abntnicntis moved longitmlinally oil? said here, a pipe oi? an air brake system comnuinicating with said valve closin o; pressure chamber, means for admitting fluid pressure to said chambers and system, an inlet valve for controlling the passage 01': fluid, to andftrom said valve opening}; pressure chamber in a manner to cause the fluid pres sure in said last mentioned chamber to move sai d abutment in one direction lonoitudinallv' valve when the vent in the system is closed ber within said casing, an outlet valve como municating with said valve opening pressure chamber,means carried by said abutment and connected to said valve for opening and closing the valve when said abutment is moved longitudinally ot said bore, a pipe of an air brake system communicating with said valve closing pressure ohan' ber, means for admitting liuid 1nessure to said chambers and sys tem an inlet valve for controlling the passage oi? liuid to and from said valve opening pressure chamber in a manner to cause the fluid pressure in said last mentioned chamber to move said abutment in one direction longitudinally of said bore to open said outlet valve when a vent in said system is opened and the pressure in said valve closing pressure cham her is reduced, interchangeablc means for controlling; the passage of fluid to the said valve closing pressure chamber and said system in a manner to cause the fluid pressure in the said valve closing pressure chamber to move said abutment in the opposite direction longitudinally of said bore to close said outlet valve when the vent in the system is closed and pressure in the said valve'closing pressure chamber is restored, means carried by said abutment for opening said inlet valve, adjustable means for limiting the movement of said abutment in said one direction, and means formed in said casing for limitingthe movement of the'abutment in said opposite direction.

A l'luid pressure operated valve compris inn a casing having a centrally disposed bore exteiuiinp; longitiulinally 'therethrough, a cap secured to said casing in a manner to close one end of? said bore, a valve hitting secured to the opposite end, (it said casing and having a assago extending longg'itiulinally there through and a valve seat formed therein, a signalling device comnnmicating with said passage, a valve member slidably mounted in said fitting and co-operable with said valve seat for PITGVGIltlIIg' the passage of fluid to said signalling device a movable abutment positioned in said bore in a manner to form a valve opening pressure chamber and a valve closing pressure chamber within said casing, means carried by said abutment and connected to said valve member in a manner to permit of the relative movement ofsaid means with respect to said member, means for admitting fluid under pressure to said chambers for moving said abutment in one direction or the other according to the relative fluid pressure in the respective chambers, an inlet valve for controlling the admission oit' :liuid to said valve opening pressure chamber, means carried by said abutment for actuating said inlet valve, and a plurality oi tubes having variously d li'erent ed in sziftitting ano co-operable i ith said valve seat for preventing the passage of fluid to said signalling device, a movable abutment positioned i said bore in a manner to term a valve opening and signal operating pressure chamber and a valve closing pressure chamber Within said casing, a rod carried by said abutment and adjustable with respect thereto, said rod being connected to said valve member in a manner to permit of the relative movement of said rod with respect to said member, resilient means associated with said member and roe and adapted to hold said member yieldingly in one direction with re spect to said rod, means for admitting fluid under pressure to said chambers for moving said abutment in one direction or the other according toithe rela ive iluid pressure in the respective chambers for moving said valve me ,er into and out of engagement With saidvalve seat, means for straining the fluid admitted to said chambers, an inletvalve for controlling the admission of fluid to said valve opening and signaloperating pressure chamber, saio abutment having means termed thereon and co-operahle with the stem of said inlet valve to open the inlet valve when the said valve member is removed from said valve seat, and to permit the inlet valve to close when said'valve member is in engagement with said valve seat.

6. A fluid pressure operated valve comprising a casing having; a longitudinal bore and a distributor chamber formed therein, a in ov-- able abutmentpositioned in said bore in a ing pressure chamber and said distributor nal device operatively conchamber, a r nected to said valve opening pressure chamher, an outlet valve member operatively con- 2" V ge, a valve member slidably mount nected to said abutment for controlling the passage otfluid pressure to said signal device, an inlet valve positioned between said valve opening pressure chamber and said distributor chamber, means carried by said abutment for actuating said inlet valve, and means for controlling the passage of fluid pressure from said distributor chamber to said valve closing pressure chamber and said pipe, said means comprising a plurality of tubes ha ving openings of variously dil'l'erent cross sectional areas termed therein and adapted to be positioned interchangeably in said casing between said distributor chamber and said valve closing pressure chamber.

7. A fluid pressure perated valve comprising a casing having a longitudinal bore and a distributor chamber formed therein, a cap adapted to close one end of said bore, a movable abutmentpositioned in said bore in a manner to form a valve opening pressure chamber and a valve closing pressure chamber within said casing, said pressure chambers being adapted to communicate With said distributor chamber, a pipe of an air brake system communicating with said valve closing pressure chamber and said distributor chamber, means for admitting fluid under pressure to said chambers and said pipe, means for straining said fluid in its passage to said chambers and pipe, a signal device operatively connected to said valve opening pressure chamber, an outlet valve operativcly connected to said abutment for controlling the passage of fluid pressure to said signal device, an inlet valve positioned between said valve opening pressure chamber and said distributor chamber, means carried by said abutment t'or actuating the said inlet valve, means adjustably mounted in said cap for limiting the movement of said abutment in one direction to vary the opening of said inlet valve, and means for controlling the passage of Fluid pressure from said distributor chainher to said valve closing pressure chamber and said pipe, said means comprising a plurality of tubeshaving openings of variously different cross sectional areas formed therein and adapted to be positioned interchangeably in said casing between said distributor chamher and said valve closing pressure chamber.

8. A fluid pressure operated valve comprising a casing having a bore and a distributor chamber formed therein, means for closing one end of said bore, a movable abutment positioned in said bore in a manner to form a valve opening pressure chamber and a valve closing pressure chamber Within said casing, an'outlet valve positioned in the opposite end of said bore and adapted to communicate with said valve opening pressure chamber, said valve being vopeiatively connected to closed therebv when the abutment is moved longitudinally of said bore, a pipe of an air brake system connnunicating with said valve closing pressure chamber, vmeans tor admitting fluid under pressure to said chambers and. said system in a n'ianner to cause the fluid pressure in said valve opening pressure chamber to open said valve when a vent in said system is opened and. the fluid pressure in sai d valve closing chamber is reduced, and to cause the fluid pressure in said valve closing pressure chan'iber to close said valve when the vent in said systen'i is closed and pressure in said valve closing pressure chamber re stored, an inlet valve for controlling the passsage of fluid to and from said valve opening pressure chamber, means for actuating said inlet valve, and means for varying the duration O'ii time between the closing ol the vent in said system and the closing of said outlet valve, said means comprising a pluralit olf tubes having openings or variously different cross-sectional areas formed therein and adapted to be positioned interchangeably in said casing between said distributm' chamber and said valve closing, pressure chan'iber and pipe.

9. A fluid pressure operated. valve comprising a casing havinga plurality of chambers formed therein, a valve conununicating; with one of saidchambers, a pipe of the train line of an air brake system coiniuunicating; with the other of said. chanibers, means for admitting fluid under pressure to saidchambers and said train line in substantially equal degrees of pressure, valve actuating means positioned between said chambers, means :lor controlling the passage of fluid to said chambers and'said train line and from one of said chambers in a manner to cause the fluid pressure in one of said chambers to open said valve when vent in said train line is opened and to cause the fluid pressure in the other oi said chan'ibers to close said valve when the vent in the train line is closed, and means asi-aociated with said valve actuating means torassisting the fluid pressure in said other of said chambers to close said valve. I

10. A fluid pressure operated valve comprising, a casing having; a bore and a distributor cluiniber formed therein, n'ieans for closing one end, ot said bore, a movable abutment positioned in said here in a manner to.

form a valve opening pressure chamber and a valve closing pressure chamber within said casing, anoutlet valve positioned in the opposite endot said here and adapted to commimieate with saidvalvc opening pressure chamber, said alve being operatively con.- nected to said abutment in a manner to be opened and closed thereby when the abutment is moved longitudinally oi? said bore, a pipe oi. an air brake system communicating with said valve closing pressure chamber, means for admitjh fluid under pressure to said chambers and said system in a .n'ianner to cause the fluid pressure in said valve opening pressure chamber to open said valve when a vent in said system is opened and the fluid pressure in said valve closing chamber is reduced. and to cause the fluid pressure in said valve closing chamber to close said valve when the vent in said system is closed and. the pressure in said valve closing chamber restored, an. inlet alve for controlling; the passage of fluid to and from said valve opening pressure chamber, means formed on said abutment :lor aetijiating said inlet valve, and means for 'arying the duration of time between the closing: of the vent in said system and the closing; 0'? said outlet valve.

In testimony whereof I have signed my nau'ioto this specification, on this 7th day of Fcbruary'A. l). 1928.

PATRICK M. GRANT. 

